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<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <button>点击</button>
    <script>
        // let btn = document.querySelector("button")
        // btn.onclick = function () {
        //     alert("匿名")
        // }



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            alert("立即执行1")
        })();
        (function() {
            alert("立即执行2")
        })();
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</html>